Linear motion potentiometer actuator



Sept. 2, 1969 M. w. BANG 3,465,277

LINEAR MOTION POTENTIOMETER ACTUATOR INVENTOR.

M06NS 14 BANG 2 Sheets-Sheet l Filed Aug. 15, 1967 Sept. 2, 1969 M. w. BANG LINEAR MOTION POTENTIOMETER ACTUATOR 2 Sheets-Sheet 2 Filed Aug. 15, 1967 INVENTOR. 'MOGfA/SMZ BA/VG ATTORNA-KS.

United States Patent 3,465,277 LINEAR MOTION POTENTIOMETER ACTUATOR Mogens W. Bang, Ridgway, Pa., assignor to Stackpole Carbon Company, St. Marys, Pa., a corporation of Pennsylvania Filed Aug. 15, 1967, Ser. No. 660,652 Int. Cl. H01c /02, N02

US. Cl. 338-183 8 Claims ABSTRACT OF THE DISCLOSURE It is among the objects of this invention to provide a linear motion potentiometer, in which very fine adjustments of the bridging contact along the resistance element can be made very easily.

The invention is illustrated in the accompanying drawings, in which:

FIG. 1 is a front view of the potentiometer;

FIG. 2 is a side view thereof with part broken away;

FIG. 3 is a cross-section taken on line III-III of FIG. 1;

FIG. 4 is a fragmentary front view of a modification;

FIG. 5 is a central longitudinal section;

FIG. 6 is a cross-section taken on the line VI-VI of FIG. 5;

FIG. 7 is an end view, partly broken away in section of a further embodiment of the invention; and

FIG. 8 is a front view of this last embodiment.

Referring to FIGS. 1 to 3 of the drawings, the long rectangular housing 1 of the potentiometer may be formed from a molded plastic or other suitable rigid material. The housing preferably is made from two molded half sections that have meeting edges extending from front to back across the end walls of the housing and lengthwise along its back or base. The half sections are joined together in any suitable manner, such as by adhesive for example. The front or top of the housing is provided with a centrally located recess 2 extending lengthwise of the housing for nearly its full length. Extending lengthwise along the central portion of the recess is a slot 3 with parallel sides.

Slidably mounted in the slot for movement lengthwise of the housing is a rectangular slide 5 that has side flanges 6 inside the housing in engagement with the inner surface of the front wall at opposite sides of the slot. Extending from the center of the slide toward the back of the housing is a post 7, on which is mounted a coil spring 8 that serves as a bridging contact. This coil engages a metal collector strip 9 and an electrical resistance strip 10 at opposite sides of the inside of the housing. The collector strip is provided with an integral terminal 11 that extends through the back of the housing, while each end of the resistance strip is connected to a metal terminal 12 likewise extending through the back. The resistance terminals may take the form of spring clips that clamp onto the opposite ends of the strip as shown in FIG. 3.

In order to move the slide back and forth to adjust the potentiometer, the center of the slide is provided with an integral pin 14 that projects away from the housing. Rotatably mounted on this pin is a knob 15 that has an inner portion disposed in housing recess 2 and provided with gear teeth 16. These teeth mesh with a row of rack teeth 17 projecting from one side wall of the recess. When the knob is turned, the meshing teeth compel it to travel lengthwise of the housing and thereby move the slide accordingly. For small knobs, it is preferred to provide them with a kerf 18 to receive a screwdriver for turning them. It will be seen that it is much easier to control the movements of the slide by rotating the knob than it would be by merely pushing the slide along the slot in the absence of the gear. In other words, it is easier to turn the knob a very few degrees in order to move the slide a slight distance than it is to push the slide the same small distance.

'Ihe knob also serves the purpose of holding the slide in the housing slot. This is done by providing the knob with an axial passage 20 having an enlarged outer end portion forming a circular socket 21 that receives the enlarged spherical head of pin 14. To permit the knob and pin to be assembled, the pin is provided with an axial slot 22 extending inwardly from its outer end. When the flaring wall at the inner end of the knob passage is pushed against the head of the pin, the two parts of the pin are squeezed together and slide through the passage until they can spread out again in the knob socket. This locks the knob and pin together, but permits the knob to rotate. The knob holds the flanges of the slide against the front wall of the housing, and the pin holds the knob against the base of the housing recess. Assembling of knob and slide is merely a matter of snapping them together.

In the modification shown in FIGS. 4, 5 and 6, the slide 25 has an outer portion that engages the front of the housing at opposite sides of the longitudinal slot 26 in the potentiometer housing 27. In other words, the slide is provided with lateral grooves 28 receiving the side walls of the slot so that the slide can move neither inwardly nor outwardly. The exposed portion of the slide is pro vided with a gap 29, at the center of which there is a pin 30 integral with the slide but extending outwardly away from it. Rotatably mounted on this pin is a knob 31 that may be held in place by a split head on the outer end of the pin in a socket 32 at the outer end of the passage through the knob.

The inner end portion of the knob is reduced in diameter and extends into the gap 29 in the slide. This reduced portion is provided with gear teeth 34 that mesh with rack teeth 35 projecting from one side wall of the recess 36 extending along the front of the housing. When the knob is turned, the gear will travel along the rack and thereby move the slide lengthwise of the housing. Inside the housing, the slide carries a bridging contact 37, which may be in the form of a coil spring seated in a frame 38 forming an integral part of the slide. This contact engages a metal collector strip 39 and a resistance strip 40 extending along opposite sides of the inside of the housing.

A further embodiment of the invention is shown in FIGS. 7 and 8. The slide 42 again is provided with a central pin 43, on which a knob 44 is rotatably disposed, but in this case the knob does not have to be locked onto the pin because it is held in place by projecting through a slot 45 in a mounting panel 46 in front of the potentiometer housing 47. The inner end of the knob is provided with a flange 48, the outer side of which engages the back of the panel while the inner end of the knob engages the body of the slide. The parts are held in this position by a circuit board 49, into which the terminals 50 of the potentiometer are plugged. The circuit board is rigidly mounted a fixed distance from the panel in any suitable manner.

Another distinction between this potentiometer and the ones described above is that the inner end of the knob does not project into a recess in the front of the potentiometer housing and the housing is not provided with rack teeth. Instead, one of the side walls of panel slot 45 is provided with rack teeth 52, some of which always register with gear teeth 53 on the knob. When the knob is turned, the rack teeth force it to move along the panel slot and thereby move the slide lengthwise of the potentiometer housing. If desired, the panel may be provided with two or more slots as shown, to accommodate the knobs of a corresponding number of potentiometers.

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A linear motion potentiometer comprising an elongated housing having a front and back connected by side walls, the front of the housing having a longitudinal slot therein, resistance and collector elements disposed in the housing lengthwise thereof, a slide disposed in said slot and movable lengthwise thereof, a bridging contact inside the housing carried by the slide in sliding engagement with said elements, a pin rigidly connected to the slide and projecting away from the front of the slot, a knob provided with an axial passage therethrough receiving said pin and having an enlarged outer end portion forming a circular socket, the outer end portion of the pin being enlarged to form a head seated in said socket, the knob having a portion provided with gear teeth, and a row of rack teeth that extends lengthwise of said housing at one side of the knob, said gear teeth meshing with the rack teeth so that when the knob is turned its gear teeth will travel along the row of rack teeth and move the slide along said slot.

2. A linear motion potentiometer according to claim 1, in which said slide is provided with lateral flanges inside the housing, and said knob holds said flanges against the front wall of the housing.

3. A linear motion potentiometer according to claim 1,

in which said pin is integral with the slide and is provided with an axial slot extending inwardly from its outer end to permit the two halves of the pin to be sprung together so that said head can be passed through the knob passage and into said socket.

4. A linear motion potentiometer according to claim 1, in which the front of said housing has a longitudinal recess therein receiving the gear tooth portion of said knob, and said rack teeth project from one side of the recess toward the knob.

5. A linear motion potentiometer according to claim 4, in which said knob overlies the housing at opposite sides of said recess and engages the housing only in the recess.

6. A linear motion potentiometer according to claim 4, in which said slide is provided with lateral grooves receiving the side walls of said slot to support the slide, the exposed portion of the slide being provided with a gap beside said pin for receiving said gear teeth.

7. A linear motion potentiometer according to claim 1, in combination with a panel provided with a slot receiving the gear tooth portion of said knob and extending lengthwise of said housing, one side of said panel slot being provided with said row of rack teeth projecting toward the knob.

8. A linear motion potentiometer according to claim 7, in which the inner end of said knob is encircled by an integral flange between said gear teeth and the housing, and said flange engages one side of said panel.

References Cited UNITED STATES PATENTS 3,362,004 1/1968 Bang 33s 1s5 2,091,371 8/1937 McMaster 338181 789,456 5/1905 Rupley 338-182 LEWIS H. MYERS, Primary Examiner A. T. GRIMLEY, Assistant Examiner US. Cl. X.R. 338184, 199 

